A brave son and a Good Samaritan fought off a maniacal Queens man as he slashed his wife with a meat cleaver this morning, cops said.

The couple were fighting in their Flushing apartment on Parsons Boulevard, when husband Kang Wang, 53, attacked his wife, Huizhen Liu, 52, at about 5:55 a.m., sources said.

He struck her repeatedly on the head with the cleaver until the couple’s son — Nianwen Wang, 22 — hit him with a two-by-four piece of wood and chased him out of the house, sources added.

Liu ran out into the street but the deranged Wang chased her. That’s when a Good Samaritan driving by saw the man wielding the cleaver, pulled over and beat him repeatedly with an ice scraper until police arrived, sources said.

EMS rushed the woman to New York Hospital Queens in very critical condition.